[throw310822]

There can be also a softer version of it, which is that cultural richness and focus on education are easily transmitted within families. A society that doesn't value culture and education is going to produce less educated families with even less educated children.

[rayiner]

It’s also true that IQ is both real and highly heritable. The military uses what’s essentially an IQ test to screen out the bottom 15% or so of the population: https://www.psychologytoday.com/us/blog/after-service/201801.... The military has found that people with aptitude test scores below the cutoff can’t be trained to competently perform any job in the military.

IQ is also highly heritable: https://pmc.ncbi.nlm.nih.gov/articles/PMC5985927.

[snowwrestler]

Genetic heritability, which is a subset of heritability, does not generally mean what people think it means, though. To the extent IQ can be attributed genetically to parents, it does not imply a "compounding" effect where smart people continuously have smarter kids and dumb people have dumber kids. This can understood by analogy to other personal traits like eyesight, height, weight, hair color, etc. which vary within a range across generations with occasional unpredictable outliers. This is why folks who do test for intelligence, have to test each person individually and not just rely on bloodline tracking.

[xyzzyz]

Yes, but since the heritability is high, the average IQ of the children will be close to the average IQ of the parents, despite the fact that it will tend to regress towards the mean.

[snowwrestler]

That’s not how genetics works. It’s not a simple averaging scheme.

[xyzzyz]

That’s exactly how it works in the standard additive model of heritability, and we have lots of empirical evidence that heritability of intelligence matches that model very well.

[DiscourseFan]

IQ correlates most strongly with socioeconomic class, with members of the same ethnic group scoring higher over the decades as that ethnic group as a whole becomes wealthier.

[oa335]

Socioeconomic status limits genetic potential. Thus the effects of SES dominate for those in poverty, but heritability dominates for those with higher SES.

For the intuition think of height - a malnourished child will not reach their “genetic” height. A fully nourished child will be limited by their “genetics”. Why wouldn’t other biological characteristics be similar?

https://en.wikipedia.org/wiki/Scarr%E2%80%93Rowe_effect

[rayiner]

Note that at what you’re describing is a hypothesis and at least some studies have failed to identify empirical support for it: https://www.sciencedirect.com/science/article/pii/S027656242...

[rayiner]

Exactly the opposite is true. Adoption studies have been used to isolate the effect of SES itself, and the contribution of that factor is low: https://www.sciencedirect.com/science/article/abs/pii/S01602... (“Proportion of variance in IQ attributable to environmentally mediated effects of parental IQs was estimated at .01… Heritability was estimated to be 0.42.”).

[tptacek]

This is just SIBS data. It has all the standard "Minnesota" limitations: the study is tiny, the cohort isn't demographically representative, adoption isn't itself random, nothing deconfounds the prenatal environment, and the children in the cohort are also adopted at different ages.

It's one thing to call out an interesting paper; it's another to act as if the matter has been settled simply by pointing to SIBS.

[rayiner]

The assertion I was responding to was this: “IQ correlates most strongly with socioeconomic class.”

Find me any study that shows that IQ is more strongly correlated with SES than with parental IQ.

[dgsii]

Ah, yes, the IQ test; the universal, unbiased gauge of intellect across all cultures.

[jeremyjh]

It isn't that, but it is one of the strongest predictors of success in the US military.

[hirvi74]

Compared to what though? Also, how is success in the military even defined? Highest rank? Most years served? Least injuries? The highest body count? Lowest double-digit APR% on 2018 Mustang with a rebuilt title?

[jeremyjh]

You can learn about these things by following the links given by the GP of my comment and reviewing the studies they reference. The other strongest criteria of success was the time of their two-mile run (at their specific age of enlistment).

[hirvi74]

I read the links, and the answers are still unsatisfactory.

Here is the abstract from the original paper: https://journals.sagepub.com/doi/abs/10.2466/pms.1989.69.1.2...

> The purpose of this research was to assess how well success in early combat training was predicted by scores on a test of general intelligence

It seems this research pertains to early combat training and not broad, post-training success in one's military career. Not to mention the research is essentially predicting test performance from test performance. I imagine the same predictions can be made about one's two-mile run and one's three-mile run.

> Analysis indicated that intelligence test scores AND run time significantly predicted success, each adding to the prediction provided by the other.

Which is not surprising. It shows that intelligence is just one of the multiple contributing factors. Being exceptionally tall is essential in the NBA, but being exceptionally tall, alone, is insufficient to make it to the NBA.

[hmmmmmmmmmmmmmm]

It loses its signal once you reach triple digits. You don't want someone with <80 but it tells you nothing about someone with 120 or 160.

[jeremyjh]

They eliminate the bottom third of applicants by ASVAB score which would mean an IQ of 93 if it translated exactly (ADVAB to IQ and SAT is only about 0.8 correlation). That is the minimum to get in to do any job at all for a minimum enlistment contract. So to talk about statistically significant career success predictors you would have to get into the low three digits, just looking at nothing but the math of IQ distributions. A cut-line of 80 would only drop the bottom 9% of the general population.

[alecco]

I call BS. From my extensive anecdata:

No amount of education, experience, and grit can turn a 100 IQ person into Einstein. IQ is a massive multiplier.

[hirvi74]

Do we even know what turns someone into an Einstein? The sheer reason you even mention Einstein is because he was beyond exceptional. There have been millions of people to walk the face of this planet with astronomical IQs, but there has only been a handful of Einsteins, von Neumanns, Eulers, Mozarts, etc.. So few that the uttering of the names of these individuals carries strong meaning.

It's also worth noting that none of these individuals ever took an IQ test. Their genius is entirely recognized through their work. Which again raises the question of what exactly IQ testing and what IQ is adding to our understanding of exceptional ability.

It appears that over a century of research in psychometrics has demonstrated nothing we already could not infer. We do not need some boring puzzle test to tell us someone with Down syndrome will not be a Nobel Prize winner. Nor do we need some boring puzzle test to tell us that von Neumann or Mozart had godlike childhood abilities and could maybe make large contributions for humanity.

[dgsii]

Sure, but what has that got to do with “IQ is also highly heritable?” which, in this context, suggests intelligence is something innate and biological, rather than recognizing an IQ test as a gauge skewed by culture and socioeconomic status.

[jeremyjh]

Well, that was a different reference in GP's post. You can go read it. Heritability is definitely a thing, but far from the only thing and it isn't simple Mendelian inheritance - there are many components to intelligence that reflect differently in gene transfer and so while you can see a correlation in specific individuals and their immediate ancestors there are lots of exceptions and its probably a mirage - if seen at all - in any large demographic. See my other comment on the problems with eugenics in this thread.

[tptacek]

I'm trying to understand your comment. You write: "heritability is definitely a thing". I think I agree? What thing is it you're saying heritability is?

[rayiner]

Attacking IQ test is like vaccine denialism. People don’t like the fact that requiring individuals to cooperate can enhance health outcomes for the group as a whole. Similarly, people don’t like the idea that some individuals are just born smarter than other individuals.

[hirvi74]

> People don’t like the fact that requiring individuals to cooperate can enhance health outcomes for the group as a whole.

I am not certain where you are deriving this claim from.

> Similarly, people don’t like the idea that some individuals are just born smarter than other individuals.

Nor this claim, as well.

I have had many discussions on the topic of IQ, and I have never once seen anybody ever argue that there is no variance in human intelligence. There is a large range of variance in every human attribute. That is not the focus of the debate. Rather, most of the debate seems to be surrounding the construct validity of IQ. Statistical validity != construct validity.

[dgsii]

I don’t mean to suggest that an IQ test doesn’t have any value, only that they don’t account for many subtleties across (sub)cultural boundaries and are too heavily considered in determining one’s intellect, and often worth, by society.

You’re using Motte-and-Bailey tactics to conflate IQ test results with vaccines denialism, on the basis that they are both “for the greater good”, which conveniently paints my point in a certain political light. How exactly does selectivity on the basis of IQ test results “enhance health outcomes for groups as a whole”? Maybe you could back up this argument with some historical context.

> “Similarly, people don’t like the idea that some individuals are just born smarter than other individuals.”

What data do you have to support this claim? And how much of this inherent intellect factors into IQ test results?

[tptacek]

Attacking IQ is nothing whatsoever like vaccine denialism. The valid/meaningful uses of IQ are widely debated in several hard science fields. That's not true of vaccines.